A widely publicized statistic showing that charter schools do a poor job of retaining their special education students was based on flawed data, the city’s Independent Budget Office has admitted."

“The agency reported in January that 80 percent of special education students identified at the start of kindergarten in 2008 left their charter school within three years. But the real figure is likely different, since the IBO only accounted for students receiving full-time special education services—omitting students with less-severe needs….”

Chalkbeat reporter Sarah Darville goes on to note that the error “raises questions about how committed the agency is to accuracy, given its role as a nonpartisan education data watchdog.”

There’s a phrase in media slang for a story so juicy that reporters would rather not scrutinize it too carefully: “Too good to check.” That is apparently how the IBO saw its finding about charter schools and special education. Whether out of a tacit hostility to charter schools, or a misguided desire to show “mixed results,” it seems the IBO didn’t want to think too hard about the 80% figure.

Why else would the agency calculate that there were only 25 charter school kindergarteners in special education in all of New York City, and not double-check the underlying data?

Why else would the IBO wait to admit error until it was confronted by a reporter?

The DOE needs a data watchdog, but the IBO is blind in one eye. As a result, the charter attrition study’s real value was overshadowed by stuff like this: